Method and device for advertising routing information and method and system for implementing packet routing

1. A method for implementing packet routing, wherein a core router in a backbone network advertises routing information that carries address information of the core router, and a border router that receives the routing information, if an edge network connected with the border router comprises a more detailed address prefix covered by an address prefix advertised in the routing information, registers a mapping relationship between the more detailed address prefix information and the border router address at the core router, comprising: receiving, by the core router, a packet which is forwarded by a router to the core router according to aggregate address prefix information advertised by the core router in a routing table of the router; searching for, by the core router, a best route matching a destination address of the packet according to the mapping relationship between address prefix information and border router address information registered on the core router, wherein the best route is a route in longest match with the destination address; and forwarding, by the core router, the packet to a corresponding border router via a tunnel destined for the border router according to the obtained best route.

2. The method of claim 1 , after the corresponding border router receives the packet, further comprising: continuing, by the border router, routing and forwarding the received packet until the packet reaches a destination host.

3. A system for implementing packet routing, comprising a core router and a border router, wherein: the core router is adapted to: store a mapping relationship between an address prefix and a border router address, wherein the address prefix is an address prefix comprised in an edge network connected with the border router and also a more detailed address prefix covered by an address prefix in routing information advertised by the core router; search for information of a more detailed address prefix corresponding to a destination address of a received packet according to the mapping relationship and forward the packet via a tunnel destined for a corresponding border router according to the border router address information mapped to the more detailed address prefix; and the border router is adapted to: register a mapping relationship between a more detailed address prefix information and the border router address at the core router, if an edge network connected with the border router comprises the more detailed address prefix covered by an aggregate address prefix advertised by the core router.

4. A method for implementing packet routing, wherein a core router in a backbone network advertises aggregate prefix routing information that carries address information of the core router and a border router that receives the routing information, if an edge network connected with the border router comprises a more detailed address prefix covered by an address prefix advertised in the routing information, registers a mapping relationship between the more detailed address prefix information and the border router address on the core router, comprising: searching for, by the border router, a best route matching a destination address of a packet requiring forwarding, and if the best route is the aggregate prefix route, requesting the core router that advertises the aggregate prefix route for border router address information corresponding to an address prefix in longest match with the destination address of the packet according to the received address information of the core router; searching for, by the core router, the address prefix in longest match with the destination address of the packet and sending border router address information corresponding to the address prefix to the border router that initiates the request according to the mapping relationship; and forwarding, by the border router, the packet via a tunnel destined for a border router indicated in the address information upon reception of the address information.

5. The method of claim 4 , further comprising: continuing, by the border router indicated in the address information upon reception of the forwarded packet, routing and forwarding the packet until the packet reaches a destination host.

6. A system for implementing packet routing, comprising a core router, an ingress tunnel border router, and an egress tunnel border router, wherein: the core router is adapted to: store a mapping relationship between an address prefix and a border router address, wherein the address prefix is an address prefix comprised in an edge network connected with the ingress tunnel border router and also a more detailed address prefix covered by an address prefix in routing information advertised by the core router; receive a mapping request message sent by the ingress tunnel border router, wherein the message requests border router address information corresponding to an address prefix in longest match with a specified destination address, search for the address prefix in longest match with the destination address and determine border router address information corresponding to the address prefix according to the mapping it stores, and send the border router address information to the ingress tunnel border router that initiates the request; the ingress tunnel border router is adapted to: upon reception of a packet, if the best route corresponding to the destination address of the packet is an aggregate prefix route, request the core router that advertises the aggregate prefix route for border router address information corresponding to an address prefix in longest match with the destination address of the packet; forward the packet via a tunnel destined for an egress tunnel border router indicated in the border router address information according to the border router address information returned by the core router; and the egress tunnel border router is adapted to: receive the packet and route and forward the packet according to routing table of the egress tunnel border router.